# Plugin **square_loop - calculation of a rectangular loop inductance.**

The inductive element in the form of a rectangular loop large size is quite often used as induction sensors in geological exploration, on the road etc.

There are several little different from each other empirical formulae for calculating the inductance as a rectangular loop of wire. In the plugin square_loop following formula is used:

where:

- L - inductance (μH);
- a, b - loop sizes from center to center of wire (m);
- r - the radius, half of the wire diameter (m)
- µ - magnetic permeability of the wire;
- c - the diagonal of the frame is calculated by the formula:

The permeability of some metals:

Copper | 0.999994 |

Aluminum | 1.000022 |

Steel | 100 |